I've discovered that this is the most effective approach to accomplish it.
Launch TikTok on your iPhone.
You may locate the video you wish to save by swiping up or searching for it.
Tap the Share button.
Instead of the Save Video option, scroll right and choose the Live Photo option. The live photo will be exported to your Camera Roll in the iOS Photos app.
Open the Photos app and open the recently exported live photo.
Tap the Share button in the lower left corner and choose Save as video.